Header for a forage harvester

ABSTRACT

A coppice header for a forage harvester adapted to be mounted on and powered by a forage harvester. The header including at the front side two circular rotatable knives, a feeding drum being mounted above each knife, said drums being rotatable about the same rotation axis as the respective knives, wherein each feeding drum is equipped with one or more flat hook-shaped extensions adapted to grab the cut stems in the region immediately above the rotatable knives. The header may also be provided with a front feed roll placed behind the knives and two additional feed rolls placed behind the front feed roll, wherein the front feed roll is equipped with guiding blades along the length of the feed roll. The blades have a central protrusion, so that the blades are longer in a region around the middle of the blade than at the lateral ends of the blades.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority under 35 U.S.C. §119 to EP08.170.940.4, filed on Dec. 8, 2008 titled, “Header for a ForageHarvester” and having Pierre E. Teetaert, Didier O. M. Verhaeghe andSandor W. van Vooren as inventors. The full disclosure of EP08.170.940.4 is hereby fully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to forage harvesters, in particular to aheader adapted to be mounted at the front of such a harvester, as ameans for cutting and collecting coppice crops, in particular brushwoodor young trees such as poplars or willows, which are currently grown forthe production of biomass fuel.

STATE OF THE ART

A forage harvester comprises feed rolls at the front of the machine, andbehind said feed rolls a cutting drum to comminute crops that are beingfed to said cutting drum by the feed rolls. A header is mounted in frontof the feed rolls, said header comprising cutting means and possiblyadditional conveying means, in order to cut the crops from the land andfeed them towards the feed rolls of the harvester. Different headersexist for different crop types. Headers for harvesting coppice crops aredocumented for example in DE-A-9316683U and DE-A-202007007213U. In eachcase, the header comprises two circular knife blades arranged to cut offthe stems as close as possible to ground level. The rotation axes of theblades are positioned upright and usually somewhat inclined forwardly sothat the blades are inclined towards the ground level. Arranged torotate at a slower speed than the blades and about the same rotationaxes, are feeding drums extending above the blades and equipped withguiding means. DE-A-9316683 shows such guiding means in the form ofstraight radial extensions at the bottom of the feeding drums.DE-A-202007007213U shows a series of radial bars extending atapproximately mid-height above the knives. The latter document shows thepresence of three horizontal feed rolls inside the header itself,arranged behind the feeding drums, in order to grab the crops providedby the feeding drums, and transport these crops to the feeding andcutting drums of the forage harvester.

These existing systems are open for improvement in a number of areas.One of the occurring problems is the ‘double-cutting’ of stems, whichoccurs when the cut stems are insufficiently grasped by the verticalfeeding drums and their bottom part is cut a second time by the circularknife blades. Also, in areas where a lot of dirt is on the ground, or ona land surface covered in snow, existing systems tend to transport toomuch of this undesirable material along with the stems, which leads toan increased risk of blocking.

PURPOSE OF THE INVENTION

The present invention aims to provide a header for a forage harvester,for cutting and harvesting stem bearing crops, without suffering fromone or more of the problems highlighted above.

SUMMARY OF THE INVENTION

The present invention relates to a header for a forage harvester, asdescribed in the appended claims.

According to a first aspect of the invention, a header is provided forharvesting coppice crops, said header being adapted to be mounted on andpowered by a forage harvester, said header comprising at its front twocircular rotatable knives, a feeding drum being mounted above eachknife, said drums being rotatable about the same rotation axis as therespective knives, characterized in that each feeding drum is equippedwith one or more flat hook-shaped extensions adapted to grab the base ofthe cut stems in the region immediately above the rotatable knives.

The hooks engage the stem immediately after cutting and are able toguide the stem base inwardly from the outer half of the circular knivestowards the central area between the feeding drums. The hooks preventthe stems from sliding off the rotating knives and receiving a secondcut before being fed eventually to the drums.

The hook-shaped extensions may be arranged on a ring-shaped plate,mounted below the feeding drum and above the circular knife.Alternatively, the extensions may be integral with the feeding drums.

When the drums are provided with radially extending guiding plates, ahook-shaped extension preferably is provided at the bottom of eachradial guiding plate. The hook then guides the cut stem base directly tothe guiding plate.

According to a second aspect of the invention, a header is provided forharvesting coppice crops, said header being adapted to be mounted on andpowered by a forage harvester, said header comprising at the front sidetwo circular rotatable knives, a feeding drum being mounted above eachknife, said drums being rotatable about the same rotation axis as therespective knives, the header further comprising a front feed rollplaced behind the knives and two additional feed rolls placed behind thefront feed roll, characterized in that the front feed roll is equippedwith guiding blades along the length of the feed roll, said bladeshaving a central protrusion, so that the lengths of the blades aregreater in a region around the middle of the blades than at the lateralends of the blades.

The central protrusion enhances the transfer of the stems to the feedrolls of the header and the inlet of the forage harvester by reducingthe free space between the upright feed rolls and the envelope of thefront feed rolls.

The protrusion preferably is bent with respect to the rest of the bladefor more aggressive engagement of the base of the cut stems.

The operation of the header may further be enhanced by providinginwardly inclined guiding plates above the circular knives and/orupright blocking plates adjacent the outer surface of the upright drums.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a header according to the invention.

FIG. 2 is a perspective view of the main working components of a headerof FIG. 1.

FIG. 3 shows detailed views of a separate plate with hook-likeextensions, which may be mounted between the feeding drums and thecircular knives shown in FIG. 2.

FIG. 4 is a front view of the circular knives, feeding drums and gearboxshown in FIG. 2.

FIG. 5 is a side view of the components of FIG. 2.

FIG. 6 is a perspective view of a front feed roll in a preferredembodiment of the header of the invention.

FIG. 7 is a perspective view of the header of FIG. 1 with the feedingdrums and knives removed, in order to show a number of additionalcomponents.

FIG. 8 is a front view of a header according to the invention, in orderto illustrate the position of two lateral guiding plates, in relation tothe circular knives.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment will now be described in further detail, by wayof example only, with reference to the accompanying drawings. Thedetailed description is not limiting the scope of the invention, whichis defined only by the appended claims. In the following description,the terms ‘front’, ‘before’, etc. and ‘back’, ‘rear’, ‘behind’, etc. areconsistently used to refer respectively to the front of the header, i.e.the part where the knives are present, and the back of the header, i.e.the side that is connected to the harvester. The terms ‘horizontal’ and‘vertical’ indicate a general direction and are not limiting in a strictsense.

FIG. 1 shows a header 1 according to the invention. The header comprisesmeans for attaching the rear section of the header to a feeder unit of aforage harvester of a known type. These attachment means and the meansfor coupling the header to the power source of the harvester can bemanufactured in a suitable way according to known practice. The headeris provided with a pair of front swivel wheels 3, front guiding panels 4arranged in a convergent way with respect to the travelling direction ofthe harvester, and a push bar 5 for pushing forward the upper part ofthe stems before cutting. The main working components of the header 1 ofthe invention and their characteristic elements will be described inmore detail with reference to FIG. 2. As shown therein, two rotatablecircular knife blades 6 are present, arranged to rotate aboutsubstantially parallel rotation axes, and each powered by a hydrostaticmotor 8. The direction of rotation is indicated by the two arrows. Tworotatable feeding drums 9 are mounted above the knives 6, and arrangedto rotate about the same two rotation axes. The rotation of the feedingdrums is powered by a further hydraulic motor 10, through gearbox 7,which is mounted above the feeding drums 9. The motor 10 and the feedingdrums are adapted to rotate at an angular speed which is normally muchlower than the speed of the knives 6, to thereby gather the cut stemsinto the header. For this purpose, the feeding drums have radialextension plates 15 extending along the height of the drums, with radialbar-like extensions 16 protruding at mid-height from these plates 15.Three horizontal feed rolls 20, 21 and 22 may be arranged behind theknives, for grabbing and transporting the cut stems towards the inlet ofthe forage harvester.

According to a first aspect of the invention, additional radialextensions in the form of flat hook-like extensions 17 are provided atthe bottom portion of the feeding drums, i.e. in close proximity to theupper surface of the rotatable knife blades 6 and essentially parallelto said surface, so as to grab the base of the cut stems in the regionimmediately above the knife blades and guide the stems toward the backof the header 1. In the embodiment of FIG. 1, four hooks are present oneach feeding drum. As illustrated in FIG. 2, these hooks may be part ofa separate ring-shaped plate 18 which is mounted to the feeding drums sothat the hooks are arranged between each feeding drum 9 and thecorresponding knife blade 6. A detailed view of such a ring is shown inFIG. 3. Alternatively, the hooks may be integral with the bottom sectionof the feeding drums. The hooks are preferably arranged so that thehooks of the two feeding drums are rotating in the same plane, as isvisible in FIG. 4.

The hook-shape of the extensions 17 ensures that cut stems are gatheredvery early after cutting, and that the bases of those cut stems are heldpositively during the transport towards the interior of the header (i.e.the space between the feeding drums 9). This firm hold prevents thestems from sliding off the knife blades 6, hitting the ground and beingcut a second time. Furthermore, the height and shape of the hooks issuch that the stems are released at the appropriate moment when they aregrabbed between the feeding drums. As the stems are being draggedinward, their top portions are pushed forward first by push bar 5 andthen by the gearbox 7, until the bases of the stems flip over the heightof the hooks and are released from the hooks 17. The length and heightof the hooks is selected to make sure that this moment of release takesplace when the stems are in an appropriate position for being guidedfurther into the forage harvester. For example, when the headercomprises front and rear feed rolls 20 to 22, this position of releaseis a position which is sufficiently close to the front feed roll 20. Inthis way, it is ensured that a maximum of stems are effectively grabbedby said feed roll 20, without falling down from the knife blades 6 onthe ground, so that the amount of double-cut stems is minimized.

As seen in FIG. 3, the preferred shape of the hooks is such that eachhook has a concave side consisting of a straight portion 25, and a shortforwardly bent portion 26 at its end, whereas the convex side consistsof a curved portion 27. The short bent portion is bent forwardly withrespect to the sense of rotation of the hook extension 17 at asufficient angle in order to aggressively grab the cut stems, afterwhich the stems are supported by the whole of the hook's concave side25, 26 until the moment of release. It is clear that other hook-shapescan be used within the scope of the invention.

According to the preferred embodiment, the number of hook extensions 17corresponds to the number of radial plates 15, and each hook is providedat the bottom of one of the radial plates, the concave side of the hookextending from the bottom of the plate 15, so that optimal cooperationtakes place between the plate 15 and the hook 17. Other configurationsare however possible within the scope of the invention, e.g. non-equalnumber of radial plates and hooks, hooks but no radial plates, hooks incombination with radial guiding stems.

According to a second aspect, the invention relates to a header 1comprising a front feed roll 20, which is positioned immediately behindthe rotating knives, as is visible in FIG. 2 and more clearly in theside view of FIG. 5, and two further feed rolls 21 and 22, locatedbehind the front feed roll 20. The second and third feed rolls 21 and 22are arranged to cooperatively transport cut stems through the spacebetween these rolls. When the header 1 is mounted to the forageharvester, the level of this space is corresponding substantially to thelevel of the front feed rolls of the cutting system of the harvester.The front feed roll 20 of the header is arranged to grab the stems thatare being fed into the header by the vertical feedings drums 9. Thepowering of the three feed rolls 20, 21, 22 can be performed in a mannerknown in the art. They may be driven from the drive system of the infeedsection of the forage harvester so as to maintain speed synchronisationbetween all feed rolls and ensure an even feeding of the crop to therotating cutterhead of the harvester. In FIG. 5, it can be seen that theknives 6 are tilted slightly forward, and that the rotation axis of thefront feed roll 20 is positioned slightly above the plane of therotating knives. The presently described aspect of the invention centreson certain characteristics of the front feed roll 20. According to thisembodiment, as seen in FIG. 6, the front feed roll 20 is equipped withtransverse guide blades 30 extending along the length of the roll andpointing outwards from the circumference of the roll in a generallyradial direction (not necessarily along a radius, but pointing away fromthe roll). According to the invention, these blades are provided with acentral protrusion 31 so that the length of the blade is greater in aregion around the centre of the blade compared to the sides of theblade. Preferably, the protrusion 31 has a trapezium-shape, as shown inFIG. 6 a. The protrusion 31 is preferably centred on the middle of thewidth of the blade such that equal regions 32 of shorter blade-lengthremain on either side of the protrusion 31. The blades 30 can bestraight and oriented in radial direction, or according to a morepreferred embodiment shown in FIG. 6 b, the blades have base portions 35oriented radially and top portions 36 bent forwardly with respect to thenormal rotation of the feed roll 20. Preferably, this bent portion 36corresponds to the protrusion 31 of the blade. Hence, when a blade 30 ispresent at the top of the feed roll, the top portion 36 is bent awayfrom the feeding drums 9 and knives 6, i.e. toward the back of theheader. This ensures optimal grabbing of the stems by the front feedroll 20, as it rotates counter-clockwise in the view of FIG. 5. Thetrapezium-shape leads to lateral open spaces between the front feed roll20 and the two back rolls 21 and 22. These open spaces allow for theeasy evacuation of excessive amounts of dirt, snow or other undesirablematerials, during operation of the header. Furthermore, the inclinedportions of the central protrusion 31 provides an improved and moreequal distribution of cut stems over the width of the feed rolls.

In order to ensure optimal guidance of the cut stems towards thetrapezium-type front feed roll 20, a horizontal transition plate 41 ispreferably mounted between the knives 6 and the front feed roll 20, asshown in FIGS. 5 and 7. FIG. 7 is a view of the header with the knives,feeding drums and gearbox taken out, in order to visualize a number ofspecific components, such as the horizontal plate 41. The front feedroll 20 is visible on this figure, with the trapezium-shaped protrusions31. According to the preferred embodiment, the transition plate 41 has afirst portion 42 which is essentially parallel to the plane of thecircular knives 6 and is located underneath said knives. The front edge(i.e. pointing towards the front of the header) of portion 42 may have acurved middle portion, as shown in FIG. 7, so as to correspond to theshape of the overlapping knives. On the back edge of the plate 41, twolateral protrusions 43 are present, which are preferably bent upwards topoint towards the rotation axis of the front feed roll 20. Said lateralprotrusions 43 are arranged in such a manner that the trapezium-shapedportion 31 of the front feed roll 20 may pass between said lateralprotrusions, with a limited spacing being left between the protrusions43 and the trapezium-shaped portion 31. In this way, an optimal guidingof the stems towards the front feed roll is achieved.

According to another aspect, equally illustrated by FIG. 7 and moreclearly visible in FIG. 8, the header comprises two lateral guidingplates 50 placed one on each side of the assembled circular knife blades6, and located in a plane essentially parallel to said knives. Theseplates overlap with the rotatable knives, whilst being present above theknives and in close proximity to the top surface of the knife blades.These guiding plates 50 are instrumental in guiding stems that havegrown in a horizontal direction. This happens typically when youngerstems grow from the stump of a previously cut stem. The plates 50 aremounted against the converging guiding panels 4 of the header and have along edge 51 at the front of the plate and a short edge 52 at the back,which edges are intersecting in intersection point 53. Said point and apart of the guiding plate in the vicinity of said point overlap with thecorresponding knife.

According to another aspect, also illustrated by FIG. 7, two lateralvertical blocking plates 60 are present behind the feeding drums 9,preferably oriented at an angle towards the vertical centre plane of theharvester. The vertical blocking plates have vertically oriented edges,which are located adjacent to the feeding drums with a limited space inbetween the plates and the feeding drums. In this way, the verticalplates 60 are adapted to prevent cut stems from being rotated backtowards the front of the knives, by the rotating feeding drums.

Even though the above characteristics are shown in combination in thedrawings, the present invention is not limited to a header wherein allthese features are present simultaneously. The invention is related to:

-   -   a header known in the art, and further provided with the        hook-shaped extensions 17;    -   a header known in the art, and further provided with the        trapezium-type feed roll 20, preferably with the horizontal        guide plate 41;    -   a header known in the art, and further provided with the        horizontal lateral guide plates 50;    -   a header known in the art, and further provided with the        vertical blocking plates 60;    -   a header known in the art and further provided with two or more        of the above features in combination.

1. A header for harvesting coppice crops, said header being adapted tobe mounted on and powered by a forage harvester, said header comprisingat its front two circular rotatable knives, a feeding drum being mountedabove each knife, said drums being rotatable about the same rotationaxis as the respective knives, wherein each feeding drum is equippedwith at least one flat hook-shaped extension adapted to grab the base ofthe cut stems in the region immediately above the rotatable knives,wherein the hook-shaped extension has a concave side and a convex side,the concave side has a straight portion extending radially outwardlyfrom an axis of rotation of the hook-shaped extension, the convex sideis an outwardly curved portion, the hook shaped portion has a forwardlybent portion at a distal end of the hook-shaped extension where theconcave and convex portions intersect, the bent portion is bentforwardly with respect to a direction of rotation of the hook extension,and the bent portion is bent at a sufficient angle in order toaggressively grab the cut stems.
 2. A header according to claim 1,wherein the at least one hook-shaped extension is arranged on aring-shaped plate, said plate being mounted between the feeding drum andthe respective knife.
 3. A header according to claim 1, wherein the atleast one hook-shaped extension is integral with the feeding drums.
 4. Aheader according to claim 1, wherein the feeding drums comprise radialguiding plates along the height of the drums, and wherein the at leastone hook-shaped extension is provided at the bottom of each radialguiding plate.